Therapy (appendix 2 - Time Table) Patient will be screened, and their oral hygiene will be brought up to standard by hygienist (TP). Eligibility, Indexes and microbiological diagnosis will then be recorded by project leader (HP). If willing to participate in the study, the patients will randomly be assigned to the 4 different groups by secretary/ project coordinator (N). Group 1; One-day SRP/FDIS with antibiotics, Group 2; One-day SRP/FDIS with placebo, Group 3; SRP over 2 weeks (scaling day 1 and 14) with antibiotics, Group 4; SRP over 2 weeks (scaling day 1 and 14) with placebo. Treatment at baseline will be performed after protocol (TP)l, and maintenance controls with recording of indexes and microbiological diagnosis will be performed at 3 months, 1, 3 and 5 year post-treatment (HP). All data, Measurements, microbiological diagnoses and response to questionnaires will be sent to CodeBookMaster (PG) following each measuring session. Reliability testing of the measurer (HP) every 12 month.